Method and device for delivering medicine to bone

ABSTRACT

A method for delivering multiple substances in a delay fashion to a bone of a patient is provided. The method includes providing a cannulated bone screw, creating an aperture in the skin of a patient, and inserting the bone screw into a bone of the patient through the aperture. The method further includes delivering a first substance into the bone through the bone screw, wherein the first substance changes over time into a solid hardened material, and then delivering a second substance into the bone through the bone screw after the first substance changed into a solid hardened material. The solid hardened material of the first substance may be a permeable material that allows the second substance to transport through, or the second substance may transport through the first substance by diffusion, or may reach a desired location in the bone through pores or cracks in the hardened solid material.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.13/270,072, filed Oct. 10, 2011, now U.S. Pat. No. 9,445,852, which is acontinuation of U.S. application Ser. No. 12/822,022, filed Jun. 23,2010, now U.S. Pat. No. 8,062,270, which is a continuation-in-part ofU.S. application Ser. No. 12/427,520, filed Apr. 21, 2009, now U.S. Pat.No. 8,808,337, which is a continuation of U.S. application Ser. No.10/704,526, filed Nov. 7, 2003, now U.S. Pat. No. 7,527,611, which is acontinuation-in-part of U.S. application Ser. No. 10/682,307, filed Oct.9, 2003, now U.S. Pat. No. 7,608,062, which is a continuation-in-part ofU.S. application Ser. No. 10/620,287, filed Jul. 15, 2003, now U.S. Pat.No. 7,575,572. U.S. application Ser. Nos. 13/270,072, 12/822,022,12/427,520, 10/704,526, 10/682,307, and Ser. No. 10/620,287 areincorporated herein by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates to devices and methods for deliveringsubstances such as medicants to bones and to devices for removingmaterials from the body. More particularly, the present inventionconcerns devices and methods for delivering substances to the interioror exterior of fractured or otherwise injured bones, especially to thefracture interface thereof. The present invention also relates todevices and methods for removing materials from the interior or exteriorof injured bone. The devices may also be used to promote fusion of abone or a joint, including a peripheral joint such as a finger or aknee.

BACKGROUND OF THE INVENTION

Delivery of medicants or therapeutics to bones is an often desirable butdifficult-to-achieve process, especially if one desires to focus thedelivery to the interior of a bone or to a particular area in a bone.Delivery pins or needles, such as those disclosed in U.S. Pat. No.6,210,376, the disclosure of which is hereby incorporated by referenceherein, are sometimes used to deliver medication or other fluids intobone. Such pins are typically made of metals such as titanium or steel,and must be fabricated ahead of time for later use. Thus, it isdifficult to customize the pins for directing the delivery of medicantsor fluids to a specific area of interest within a bone. Moreover, suchpins do not serve as fixation screws for holding two or more bones orbone pieces in a fixed spatial relationship with respect to each other.

Bone screws can be used to repair or strengthen fractured or otherwisedamaged or diseased bones, often by fixing two or more bones or bonepieces with respect to each other, in which case the bone screw may bereferred to as a fixation screw. Such screws have been adapted todeliver liquids such as bone cements to the interior of a bone, and aredisclosed in U.S. Pat. Nos. 5,047,030 and 6,214,012, for example, thedisclosures of which are hereby incorporated by reference herein. Thesedevices must be fabricated ahead of time for later use, therebysubstantially limiting the ability to customize the device to the needsof an individual patient. Moreover, while these devices may be suitablefor the one-time delivery of a curable substance such as a bone cement,they provide no way to control or regulate the amount of substancedelivered. Substance delivery also cannot be directed to certain areaswithin the bone and not others without changing the location orconfiguration of the bone screw itself.

Thus, a need exists for a device capable of delivering a substance to abone, especially to specific areas within the bone, such as a fractureinterface. In addition, a further need exists for the ability tocustomize the delivery location and amount during the course of anoperation, once the bone screw is in place, for example.

SUMMARY OF THE INVENTION

In accordance with the present invention, a bone-screw insert isdisposed within or along a bone screw to provide a device for thedelivery of a desired substance to the interior or exterior of a bone orits surrounding tissues.

In some embodiments, the bone screws and the inserts are cannulatedalong at least a portion of their lengths. The bone screws arefenestrated and the inserts are either fenestrated or permeable to thesubstance to be delivered such that when the insert is disposed withinthe bone screw a delivery pathway exists whereby the substance can bedelivered from one end of the insert to the exterior of the bone screwthrough the bone-screw fenestrations. The bone-screw inserts of thepresent invention thus allow one to selectively block the bone-screwfenestrations to which substance delivery is not desired, whilemaintaining a substance delivery pathway to one or more bone-screwfenestrations to which substance delivery is desired.

In other embodiments, inserts, which may be fenestrated or permeable,are disposed along at least a portion of an exterior surface of the bonescrews. In these designs, the inserts may be connected to the exteriorsurface of the bone screws using a variety of attachment means,including but not limited to, grooves, hooks, loops, and the like. Forexample, the bone screws may have one or more exterior grooves runningalong at least a portion of their lengths and the inserts may be adaptedto fit into the grooves. The inserts may be either fenestrated orpermeable to the substance to be delivered such that when the insert isdisposed along the exterior surface of the screw a delivery pathwayexists whereby the substance can be delivered from one end of the insertto the exterior of the bone screw through permeable insert walls orinsert fenestrations.

In one aspect of the present invention the bone screw comprises afixation screw whereby two or more bones or bone pieces may be held in afixed spatial relationship with respect to each other. It may often bedesirable to deliver a substance at or near the fracture interface of abroken bone, for example. In such a case, the desired positions ofbone-screw fenestrations which will align with or match this locationmay not be known until after the bone screw has been disposed within thebone. The bone-screw inserts of the present invention thus allow one totailor a substance delivery pathway through one or more insert and/orbone-screw fenestrations after the bone screw has been disposed within abone.

In another aspect of the invention, the device comprises a reservoirwhich may serve as a source of the one or more substances to bedelivered to the vicinity of a bone. Reservoirs useful in the practiceof this invention may comprise the cannulated portions of the bone screwor insert, or they may be reservoirs that are connected to the bonescrew or insert for substance delivery. In certain embodiments thepresent invention may further comprise a pump for facilitating thedelivery of the one or more substances to the vicinity of a bone. Suchpumps may, for example, aid in the continuous or regulated flow of afluid into the bone screw or insert for delivery to the desiredlocation.

Yet another aspect of the invention provides methods for administering asubstance to a bone. In one embodiment, a method comprises introducing acannulated, fenestrated bone screw into a bone, introducing a cannulatedinsert into the bone screw cannulation, and introducing a substance tobe delivered into the cannulated portion of the insert. In anotherembodiment, a method comprises attaching a cannulated insert along atleast a portion of an exterior surface of a bone screw, introducing thebone screw into a bone, and introducing a substance to be delivered intothe cannulated portion of the insert. The methods may comprise the useof a fenestrated or permeable insert, or the use of reservoirs or pumpsto aid in substance delivery. In certain embodiments of the inventionthe insert may initially serve the purpose of preventing bone fragments,blood, fat, or other materials from entering the cannulated portion ofthe bone screw, especially during insertion of the bone screw into thebone, for example. This may then be followed by readjustment orrealignment of the insert to provide a pathway for the substance to bedelivered at a later point in time.

In another aspect of the invention, a first substance is delivered to adesired location in the bone through a bone screw. The first substancechanges over time into a solid hardened material. For example, the firstsubstance is bone void filler, such as bone cements. After the firstsubstance changed into a solid state, a second substance is deliveredinto the bone through the bone screw. In some embodiments, the solidhardened material of the first substance is permeable material. Thesecond substance can transport through the permeable material. In someembodiments, the second substance can reach to a desired location in thebone through pores or cracks in the solid hardened material of the firstsubstance. In some other embodiments, the second substance can be in aliquid state, in a gaseous state or in a mixed state. The secondsubstance may pass through the solid state of the first substance andreach to a desired location of the bone by diffusion. In anotherembodiment, the second substance may be delivered through the bone screwwhile the first substance is changing into a solid hardened material.

Another embodiment of the invention relates to a device for implantationwithin a bone. The device includes a first end, a second end and a shaftconnecting the first and second ends. The shaft defines a cannulationextending along at least a portion of the length of the shaft. Thedevice also includes a seal coupled to the shaft, the seal having aninner surface facing the cannulation of the shaft. The seal isconfigured to provide access to the cannulation following implantationof the device within the bone, and the seal is configured to self-sealafter access is provided to the cannulation.

Another embodiment of the invention relates to a system for removing asubstance from a bone. The system includes an insert having two endsconnected by a shaft, and the shaft of the insert is cannulated along atleast a portion of its length. The system includes an insertfenestration disposed along the cannulated portion of the insert. Thesystem includes a bone screw having two ends connected by a shaft, andthe bone screw is adapted to receive the insert. The system includes adevice coupled to the insert and in communication with the cannulatedportion of the insert, and the device is configured to draw materialfrom the bone through the insert fenestration into the insert.

Another embodiment of the invention relates to a method for removing asubstance from a bone. The method includes introducing a bone screw intothe bone. The bone screw has two ends connected by a shaft and a portionadapted to be attached to an insert. The method includes attaching theinsert to the bone screw. The insert has two ends connected by a shaft,and the shaft of the insert is cannulated along at least a portion ofits length. The insert includes an insert fenestration disposed alongthe cannulated portion of the insert. The method includes coupling adevice to the insert in communication with the cannulated portion of theinsert, and removing material from the bone through the insertfenestration via the device.

Another embodiment of the invention relates to a system for treating abone, which includes an insert for a bone screw or a fixation nail. Theinsert includes a shaft that extends between proximal and distal ends ofthe insert and a cap. The shaft includes an opening in the proximal endand a cannulation extending from the opening through at least a portionof the shaft. The shaft further includes a fenestration disposed alongthe cannulation such that the cannulation is configured to provide apathway for a substance between the opening and the fenestration. Thecap is fastened to and seals the opening in the proximal end of theshaft and adjoins the cannulation. The cap is configured to provide aneedle access through the cap to the cannulation following implantationof the system within the bone, and is further configured to self-sealafter the needle is removed.

Another embodiment of the invention relates to a system for removingmaterial from a bone, which includes an insert, a bone screw, and anexpandable portion. The insert includes a shaft extending betweenproximal and distal ends of the insert, a cannulation extending throughat least a portion of the length of the shaft, and a fenestrationdisposed along the shaft and connecting to the cannulation. The bonescrew includes a shaft extending between first and second ends of thebone screw. The shaft of the bone screw is cannulated. Furthermore, thebone screw is configured to receive the insert in the cannulation of thebone screw. The expandable portion is coupled to the insert and extendslaterally from the insert to contact an interior surface of thecannulation of the bone screw, which forms a seal extending between theexterior of the insert and the interior of bone screw in the cannulatedportion of the bone screw.

Another embodiment of the invention relates to a system for treating abone, which includes a fastener and an insert. The fastener includes arigid shaft extending lengthwise between first and second ends of thefastener. The first end includes an opening, and the shaft of thefastener includes a cannulation extending from the opening to the secondend of the fastener. The fastener is fenestrated with an elongate slotextending lengthwise along the shaft. The insert includes a shaftextending between proximal and distal ends of the insert, a conduitextending from the proximal end and through at least a portion of theshaft, and a fenestration disposed along the shaft and connecting to theconduit. The insert is configured to be inserted through the opening inthe first end of the fastener and is movable within the cannulation ofthe fastener.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a bone screw in accordance with thepresent invention.

FIG. 2 shows a bone screw inserted into the hip bone of a patient.

FIG. 3(a) shows a schematic cross-sectional view of a bone-screw insertwith a single fenestration.

FIG. 3(b) shows a perspective view of the bone-screw insert of FIG.3(a).

FIG. 4 shows a perspective view of a bone screw, a bone-screw insert,and an insert cap, in accordance with the present invention.

FIG. 5(a) shows a schematic cross-sectional view of a bone-screw insertwith multiple fenestrations.

FIG. 5(b) shows a perspective view of the bone-screw insert of FIG.5(a).

FIG. 6 shows a schematic cross-sectional view of a bone-screw insertwith a porous section along the length of the shaft.

FIG. 7 shows a schematic cross-sectional view of a bone-screw insertwith an internal reservoir and a cap.

FIG. 8(a) shows a perspective view of a syringe being used to provide aliquid to a bone screw disposed in a hip bone.

FIG. 8(b) shows a perspective view of a IV being used to provide aliquid to a bone screw disposed in a hip bone.

FIG. 9 shows a perspective view of a pump assembly being used to providea liquid to a bone screw disposed in a hip bone.

FIG. 10 shows a fixation nail inserted into the femur bone of a patient.

FIG. 11 shows a cross-sectional view of the fixation nail of FIG. 10.

FIG. 12 shows a perspective view of a bone-screw insert being insertedinto the fixation nail of FIG. 10.

FIG. 13 shows a fixation nail inserted into the humerus bone of apatient.

FIG. 14 shows a cross-sectional view of the fixation nail of FIG. 13.

FIG. 15 shows a perspective view of a bone-screw insert being insertedinto the fixation nail of FIG. 13.

FIG. 16 shows a fixation nail inserted into the tibia bone of a patient.

FIG. 17 shows a cross-sectional view of the fixation nail of FIG. 16.

FIG. 18 shows a perspective view of the fixation nail of FIG. 16.

FIG. 19 shows a perspective view of an IV being used to provide a liquidto the fixation nail of FIG. 16.

FIG. 20 shows a perspective view of a pump assembly being used toprovide a liquid to the fixation nail of FIG. 16.

FIG. 21 shows an insert having deflated balloons along its length beinginserted into a bone screw.

FIG. 22 shows the insert of FIG. 21 with inflated balloons disposedinside the bone screw.

FIG. 23 shows two inserts of different lengths having balloons disposedaround their shafts.

FIG. 24(a) shows a perspective view of a bone screw having and externalgroove along its length and a fenestrated insert adapted to fit into thegroove.

FIG. 24(b) shows a perspective view of the insert of FIG. 24(a) insertedinto the groove along the bone screw of FIG. 24(a).

FIG. 25 shows the bone screw and insert of FIG. 24(b) inserted into thehip bone of a patient.

FIG. 26(a) shows a perspective view of an insert adapted to fit into agroove along fixation nail.

FIG. 26(b) shows a perspective view of the insert of FIG. 26(a) insertedin a groove running along the length of a fixation nail.

FIG. 27 shows the fixation nail and insert of FIG. 26(b) inserted intothe tibia bone of a patient.

FIG. 28 shows a bone screw and an insert disposed in a bone and aperspective view of a syringe being used to provide a substance to thebone screw, according to an exemplary embodiment.

FIG. 29(a) shows a schematic cross-sectional view of a bone-screw insertwith a resealing cap, according to an exemplary embodiment.

FIG. 29(b) shows a schematic cross-sectional view of the bone-screwinsert of FIG. 29(a) following delivery of a substance to the insert.

FIG. 29(c) shows a schematic cross-sectional view of a bone screw with aresealing cap, according to an exemplary embodiment.

FIG. 30(a) shows a schematic cross-sectional view of an insert as partof a material removal system, according to an exemplary embodiment.

FIG. 30(b) shows the material removal system of FIG. 30(a) with theinsert in a second position, according to an exemplary embodiment.

FIG. 31 shows a perspective view of a bone screw including slot-shapedfenestrations, according to an exemplary embodiment.

FIG. 32 shows a fixation nail including slot-shaped fenestrationsinserted into the femur bone of a patient, according to an exemplaryembodiment.

FIG. 33(a) shows a schematic cross-sectional view of an insert disposedin a first position within a bone screw, according to an exemplaryembodiment.

FIG. 33(b) shows a schematic cross-sectional view of the insert of FIG.33(a) disposed in a second position within a bone screw, according to anexemplary embodiment.

FIG. 33(c) shows a schematic cross-sectional view of the insert of FIG.33(a) disposed in a third position within a bone screw, according to anexemplary embodiment.

FIG. 34 shows a schematic cross-sectional view of a bone screw insertedinto a bone during delivery of multiple substances in a delayed fashion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with the present invention, a bone-screw-insert isdisposed within a fenestrated bone screw or along an external surface ofa bone screw, and the combination is used to deliver desired substancesto the vicinity of a bone. The inserts are cannulated along at least aportion of their lengths and the bone screws may have an internalcannulation and/or one or more exterior insert attachment mechanismsrunning along at least a portion of their lengths. In certainembodiments, the insert may also be fenestrated or permeable to thesubstance to be delivered. The inserts of the present invention may becomprised of a single piece, or alternatively the insert may becomprised of several pieces or sections. In certain embodiments, thebone screw may be a fixation screw used to hold two or more bones orbone pieces in a fixed spatial relationship with respect to each other.The substances to be delivered may comprise medicants or therapeutics,or other substances which are desirable to deliver to the vicinity of abone. The substance or a combination of substances may be delivered tothe interior of a bone, to the exterior of a bone, to the fractureinterface between two or more broken bones, or to any other locationwhich may be facilitated by utilization of the present invention.

For the purposes of this invention, the term “cannulated” means that thescrew or insert comprises a hollow cavity disposed inside at least partof its shaft. For example, the cavity may consist of a bore beginning ator near one end of the screw or insert and extending longitudinally intothe screw or insert. Other configurations are possible, however, and thehollow cavity need not be restricted to a cylindrical shape or acircular cross-section. The cavity may extend throughout the entirelength of the screw or insert, thus creating openings at each end of thescrew or insert, or alternatively, the cavity may extend only partiallyinto the interior of the screw or insert. The shape and size of thecavity may be suitably chosen to allow delivery of the desired substancethrough the screw or insert to the bone area of interest. When it isdesired to use the cannulated portion of the screw or insert asreservoir for the substance to be delivered, for example, the cavity maybe made as large as possible so long as the screw and insert maintainthe structural integrity needed for introduction into the bone.

For the purposes of this invention, the term “fenestration” is usedbroadly to include any slot, gap, or perforation that defines an openingbetween the inside of the cannulated portion of the screw or insert tothe outside of the screw or insert whereby a desired substance may bedelivered. Thus, a fenestrated screw comprises an opening which definesa substance delivery pathway between the internal cannulated portion andthe exterior of the screw. Likewise, a fenestrated insert is one thatcomprises an opening which defines a substance delivery pathway betweenthe internal cannulated portion and the exterior of the insert. Incertain embodiments of the present invention where a fenestrated insertis utilized in combination with a fenestrated screw, at least one screwfenestration and at least one insert fenestration may be designed toalign with each other once the screw and insert are in their appropriateconfiguration and position. Alignment or coordination of an insertfenestration and a screw fenestration will define a substance deliverypathway between the internal cannulated portion of the insert and theexterior of the screw.

In accordance with the present invention, fenestrations will typicallyextend in the radial direction from the internal cannulation to theexterior of the screw or insert, but other configurations are possible.Such fenestrations are separate and distinct from the opening at or nearthe one end of the screw or insert created by the cannulation. Furtherin accordance with the present invention, the fenestrations may be anydesired shape or size desired to effect the delivery of the desiredsubstance. For example, the fenestration cross-sections may be round,oval, or square. The fenestration cross-sections may, if desired, changeshape between the inside and the outside of the screw or insert. Anynumber or combination of fenestrations may be located along the shaft orat the ends of the screws and inserts of the present invention. Theinsert fenestrations may be larger or smaller than the screwfenestrations.

An insert may have an outside diameter large enough such that theoutside of the insert is pressed snuggly against the inside of thecannulation when the insert is in a bone screw in order to prevent thesubstance to be delivered from leaking between the insert and the bonescrew and escaping through a bone screw fenestration from which it wasnot intended to escape. Alternatively, the insert may include one ormore balloons along its length. These balloons, each of which isdisposed around a portion of the insert, may be deflated when the insertis placed into the bone screw and subsequently inflated. Upon inflation,each balloon forms a seal between the outside of the insert and theinside of the bone screw. Using this construction, one or more insertfenestrations and one or more bone screw fenestrations may be isolatedbetween two inflated balloons, such that a substance delivered throughthe isolated insert fenestrations may exit only through bone screwfenestrations positioned between the inflated balloons. Inserts havingdifferent lengths and/or different balloon placements may be providedsuch that the appropriate insert and bone screw fenestrations may beisolated to provide an appropriate delivery pathway depending on thefinal position of the bone screw in a patient relative to the desireddelivery location.

As an alternative to or in combination with an insert disposed within aninternal cannulation in a bone screw, the devices provided herein mayinclude an insert disposed along an exterior surface of a bone screw.Again, the insert may be cannulated and fenestrated or permeable todefine a delivery pathway between one end of the cannulation and aportion of a bone. In this embodiment, a bone screw is provided with ameans for securing an insert along at least a portion of an exteriorsurface of the bone screw. For example, the bone screw may include atleast one groove, adapted to accept an insert, running along at least aportion of its exterior surface. Alternatively, the bone screw mayinclude one or more attachment mechanisms, such as loops, hooks or thelike, along at least a portion of its exterior surface. An insert may beinserted through these loops or hooks, securing the insert to the bonescrew. In order to ensure that the attachment elements do not interferewith the insertion of the bone screw into the bone, they are desirablyset back from the external circumferential surface of the bone screw. Ifthe bone screw includes threads, the attachment elements desirably donot extend radially beyond the threads. The bone screws may be adaptedto secure two or more inserts along their exterior surfaces. This designallows the physician to select the appropriate number and placement forthe inserts, depending on the final positioning of the bone screw in abone.

In some embodiments, a cannulated, fenestrated bone screw may becombined with an exterior insert to provide a delivery pathway betweenthe bone-screw cannulation and the exterior of the bone screw. In thisembodiment, an insert is disposed along an external surface of the bonescrew and may be used to selectively cover one or more bone-screwfenestrations in order to provide a substance delivery pathway that isappropriate based on the positioning of the bone screw in a bone. Forexample, a delivery device may include a cannulated bone screw having anexterior groove running along at least a portion of its length and aninsert adapted to slide into the groove. Fenestrations are disposedalong the groove of the bone screw to allow a substance to pass from thecannulation to the exterior of the bone screw. When a chosen insert isinserted into the groove, it selectively covers those fenestrations thatprovide a delivery pathway to areas of the bone where delivery of thesubstance is not needed, while leaving unblocked those fenestrationsthat provide a delivery pathway to areas of the bone where delivery ofthe substance is desirable.

For the purposes of this invention, the term “bone screw” is intended torefer to screws of all types which are presently known or hereafterdevised for implantation into bone. In this regard, cancellous screws,cortical screws, and machine screws are all contemplated as being withinthe scope of the types of screws useful in the practice of the presentinvention. The bone screws of the present invention will typicallycomprise threads along at least a portion of the exterior of the screwshaft, but it should be appreciated that tacks, pins, nails and the likemay also be included within the definition of a bone screw for thepurposes of the present invention, whether threaded or unthreaded. Whenthreads are present, it may be found advantageous to use self-tappingthreads, or alternatively, the threads can be pre-cut in the bone priorto bone-screw insertion.

Referring now to FIG. 1, there is disclosed a bone screw 100 having twoends 102 and 104 connected by a shaft 106, and bone screw threads 110.The cut-out of FIG. 1 reveals that bone screw 100 comprises a cannulatedportion 120, and bone screw fenestrations 130 along the length of thecannulated portion 120. It will be appreciated by one skilled in the artthat the fenestrations 130 need not be even spaced along the cannulatedportion 120, but may be arranged in a desired pattern or frequency alongthe length of the cannulated portion 120. It will be further appreciatedby one skilled in the art that one end 122 of the cannulated portion 120of the bone screw 100 is configured to accept a bone screw insert. Forexample, the bone screw 100 may comprise additional threads 140 on theone end 122 of the cannulated portion 120 to promote fixation of a bonescrew insert.

In one embodiment of the current invention the bone screw may be afixation screw used to hold two or more bones or bone pieces in a fixedspatial relationship with respect to each other. Fixation screws areknown in the art. One such device is disclosed by Tronzo, U.S. Pat. No.4,653,489, the disclosure of which is hereby incorporated by referenceherein. In accordance with the present invention, the bone screw may beused to mend peripheral skeletal fractures or osteotomies, repair aspondyloysis or an odontoid fracture, or fuse lumbar facet joints, forexample. Other beneficial uses of bone screws, and more particularly,fixation screws, will be known to one skilled in the art and are to beincluded within the scope of the present invention.

Referring now to FIG. 2, there is disclosed a bone screw 100 disposedpartially within a bone 200. Bone 200 may, for example, represent ahuman hip bone. In one embodiment, bone screw 100 is disposed withinbone 200 by rotating the bone screw 100 such that the bone screw threads110 act to pull bone screw 100 into bone 200, thereby anchoring bonescrew 100 into place.

Bone screws of the present invention may comprise any material suitablefor placement into a bone without harmful effects on the patient.Examples of suitable materials include, but are not limited to, titaniumand its alloys, tantalum and its alloys, nickel-cadmium and its alloys,steel and its alloys, plastics, absorbable materials, resorbablematerials, polyamino acids, polylactide, polyglycolide, hydroxylapatite,and tricalciumphosphate. Other materials useful for bone screwconstruction will be known to those skilled in the art, and are to beincluded within the scope of the present invention.

The device of the present invention further comprises a bone-screwinsert. For the purposes of this invention, the term “insert” is used torefer to one or more cannulated members which are disposed within thecannulated portion of a bone screw. Referring now to FIG. 3(a), theinsert 300 comprises a cannulated portion 310 which consists of a hollowcavity 320 surrounded by the insert wall 330, where the cavity and walldimensions may be suitably chosen in order to carry out the practice ofthe invention disclosed herewith. In certain embodiments, the insert maycomprise a single piece, as disclosed in FIG. 3(a). Alternatively, theinsert may comprise two or more pieces or sections that, when takentogether, form the insert of the present invention. Referring now toFIG. 3(b), when the insert 300 is a single piece, the insert comprisestwo ends, 302 and 304, connected by a shaft 306. The shaft may becannulated along its entire length, creating openings at each end of theinsert. Alternatively, the cannulation may extend only partially intothe shaft so long as the cannulation is sufficient to allow for deliveryof a substance from one end of the insert to one or more bone-screwfenestrations. One end 302 of the insert 300 may comprise threads 340which interlock with bone screw threads 140 of FIG. 1 to help fix aninsert 300 into a bone screw 100. When the insert comprises two or morepieces or sections, only one of the sections need be cannulated suchthat the insert sections, when taken together, allow for delivery of asubstance from one end of the insert to one or more bone-screwfenestrations.

In one embodiment of the present invention, the exterior dimensions ofthe insert are only slightly smaller than the interior dimensions of acannulated bone screw to provide for a tight but sliding fit when theinsert is placed into the bone screw, as depicted in FIG. 4 in which aninsert 400 is shown partially disposed within a bone screw 410. Alsodisclosed in FIG. 4 is an insert cap 415 which can be used tosubstantially seal the one end 402 of the insert 400 via insert capthreads 420 either before, during, or after the bone screw 410 andinsert 400 are put into place. The insert may have substantially thesame cross-sectional shape as the cannulated portion of the bone screw,or their cross-sectional shapes may be different. For example, theinternal bone screw cavity and the exterior surface of the insert mayhave a substantially circular cross-section. One advantage of thisembodiment is that after the insert has been disposed within the bonescrew, the insert may be rotated with respect to the screw to achievealignment of certain of the insert and bone-screw fenestrations, forexample. In another embodiment, the insert and bone screw may havesubstantially non-circular cross-sections such that the insert is notfree to rotate once it has been disposed within the bone screw. In yetanother embodiment, at least part of the insert cross-section may notmatch that of the bone screw cavity such that when the insert isdisposed within the bone screw, one or more channels are formedlongitudinally along at least part of the insert and bone screw shafts.Such channels may be useful, for example, to allow air or fluids toescape the bone screw cavity as the insert is introduced.

When substantially unimpeded delivery of a substance to one or morebone-screw fenestrations is desired, the inserts of the presentinvention may comprise one or more insert fenestrations 510, as depictedin FIG. 5(a). An insert having an appropriate number, size, shape, andlocation of insert fenestrations can be chosen by the practitionerwithout undue experimentation to provide a delivery pathway between atleast one end of the insert and the one or more bone-screwfenestrations. For example, FIG. 5(b) discloses an insert 500 comprisinga plurality of insert fenestrations 510 having a substantiallyrectangular cross-section. Alternatively, the delivery pathway mayinitiate at one end of the bone screw and pass through the insert to oneor more bone-screw fenestrations. The insert fenestrations need notmatch the bone-screw fenestrations in number, size, shape, or location,although it may be advantageous to locate at least one of the insertfenestrations such that it may be substantially aligned with at leastone bone-screw fenestrations once both the bone screw and the insert arein place.

In another embodiment of the present invention, the inserts of thepresent invention may be permeable to the substance to be delivered suchthat the substance is delivered to the exterior of the insert bydiffusion through the insert wall or through small openings in theinsert wall. Such openings may be intentionally created such as byincreasing the porosity of the insert material (e.g., by introducing aseries of pinpricks into the material), or they may exist naturally aspores in the material. Referring to FIG. 6, there is disclosed an insert600 comprising a cannulated portion 610 and a permeable material 620wherein a substance to be delivered can travel from one end 602 of theinsert to the permeable material 620. When the insert comprises amaterial that is at least partially permeable to the substance to bedelivered, the insert may or may not be fenestrated so long as deliveryof the desired substance is not completely impeded by the insert. Anembodiment of the present invention comprising a permeable butnon-fenestrated insert may be preferred when it is desired to effect acontrolled, slow release of the desired substance to a bone, or when itis desired to prevent bone fragments, blood, fat or other materials orfluids from traveling from the exterior of the insert to the interiorcavity.

When it is desired to use the cannulated portion of the insert as areservoir for the substance to be delivered, or when the substance is tobe delivered to a bone by permeation through the insert walls, it may bedesirable to make the insert walls as thin as possible. Referring now toFIG. 7, there is disclosed an insert 700 with walls 710 surrounding areservoir 720. One end 702 of the insert may be substantially sealed byinsert cap 715. For example, in one embodiment, the insert may comprisea thin-walled tube which increases the available volume for storage ofthe substance, and which also increases the diffusion of the substancethrough the insert wall. In another embodiment, the insert may comprisea film or coating on the interior surfaces of the bone-screw cavity.Inserts in accordance with this embodiment may be as thin as a fewhundred nanometers or less, which again may be beneficial for increasingthe reservoir size with the bone screw and insert cavity, and forincreasing the diffusion of the substance through the insert wall.

In another aspect of the present invention, the delivery of a substanceto a bone may alternately be controlled or directed by diminishing thecavity size within the insert so that the movement of the substance isrestricted. In this embodiment, it may be desired that the insertcannulation or insert fenestrations be a few microns (e.g., 5 microns)or less in size. Referring again to FIG. 7, there is further disclosed acannulated portion 730 of insert 700 which is diminished in size so asto restrict or limit the flow of a substance from the reservoir 720. Theexact configuration and geometry of an insert providing the desiredlevel of substance delivery can be determined by one skilled in the artwithout undue experimentation, and all such configurations are to beincluded within the scope of the present invention.

In yet another aspect of the present invention, the inserts may controlor direct the delivery of a substance to a bone through a fenestratedbone screw by substantially blocking one or more of the bone-screwfenestrations. This approach may be advantageous when it is desired todeliver the substance to a specific location with respect to the bonescrew's position within the bone. Since the exact bone-screwfenestrations which align with or match this location may not be knownuntil after the bone screw has been disposed within the bone, the bonescrew inserts of the present invention allow one to selectively blockthe bone-screw fenestrations to which substance delivery is not desired,while maintaining a substance delivery pathway to one or more bone-screwfenestrations to which substance delivery is desired. Moreover, byutilizing an insert whereby the insert fenestrations align with thebone-screw fenestrations to which substance delivery is desired, one mayachieve substantially unimpeded delivery of the substance to the area ofinterest.

In addition, the bone-screw inserts of the present invention, even whenfenestrated, may be advantageously used to significantly hinder bonefragments, blood, fat, or other materials from entering the cannulatedportion of the bone screw, especially during insertion of the bone screwinto the bone, for example. In this case it may be desirable toinitially position the insert and bone screw such that the insertfenestrations do not align with the bone-screw fenestrations. The insertmay then be subsequently re-positioned at a later time to align one ormore of the insert fenestrations with the bone-screw fenestrations tofacilitate substance delivery.

Inserts of the present invention may comprise any material compatiblewith the bone screw and able to be placed within the bone screw withoutproducing adverse effects to the patient. Examples of suitable insertmaterials include, but are not limited to, titanium and its alloys,tantalum and its alloys, nickel-cadmium and its alloys, steel and itsalloys, plastics, absorbable materials, resorbable materials, polyaminoacids, polylactide, polyglycolide, hydroxylapatite, andtricalciumphosphate. Other materials useful for insert construction willbe known to those skilled in the art, and are to be included within thescope of the present invention. When the insert comprises two or moresections, the sections need not comprise the same material. In addition,when it is desired that the insert be permeable to the substance to bedelivered, one or more of the insert sections may comprise a materialspecifically chosen to impart the desired level of permeability to theinsert.

The insert may be sold or otherwise provided in a kit containing two ormore inserts having different fenestrations or permeabilitycharacteristics. The availability of such a kit has the advantage ofallowing a practitioner to select an appropriate insert based on theparticular needs of the patient.

In accordance with the present invention, the insert is disposed withinthe bone screw to provide for a directed or controlled delivery of adesired substance to a bone. For the purposes of this invention, theterm “substance” is used to refer to one or more chemical compounds thatare useful when delivered to the vicinity of a bone. Substances may bechosen to help treat diseased bone as well as fractured or otherwiseinjured bones. Alternatively, the substance may be delivered tootherwise healthy bone to help maintain overall bone health, forexample. Representative example substances include medicants ortherapeutics such as antibiotics, chemotherapeutics, angiogenic factors,bone morphogenic proteins, bone cements and bone growth factors. Otherdesirable substances may be known or hereinafter determined by oneskilled in the art, which are to be included within the scope of thisinvention.

In certain applications of the present invention it may be desirablethat the substance be stored in a reservoir prior to delivery to a bone.Thus, it may be advantageous for the device of the present invention tofurther comprise a reservoir. For the purposes of this invention, theterm “reservoir” refers to any source of the one or more substances tobe delivered to the vicinity of a bone. For example, the reservoir maycomprise the hollow cavity created by the cannulation of the bone-screwinsert and any part of the bone-screw cannulation not occupied by theinsert, as depicted in FIG. 7 and described above. In one embodiment ofthe present invention, the substance to be delivered may be absorbedinto a sponge-like material such as a collagen, for example, which maythen be disposed within the cannulated portion of the bone screw orinsert, or both. When additional reservoir space is desired, a suitablereservoir may be connected to the cannula opening of either the bonescrew or insert. For example, FIG. 8(a) discloses a bone screw 800 andan insert 810 disposed therein, both of which are disposed within a bone820. FIG. 8(a) further discloses a syringe 830 which acts as a reservoirin accordance with the present invention to provide a substance to thebone 820 via bone screw 800 and insert 810. Another embodiment of thepresent invention, is depicted in FIG. 8(b) which discloses an IV 840which serves as a reservoir for delivering a substance to a bone via abone screw and an insert. In yet another embodiment of the presentinvention, the reservoir may be implanted beneath the patient's skin,i.e., subcutaneously.

In another aspect of the present invention, it may be advantageous forthe device of the present invention to further include a pump 920, asdepicted in FIG. 9, for delivering a substance to a bone via a bonescrew and an insert 910, and tubing 930. A pump may be utilized to aidin delivery of the substance to the vicinity of a bone by, for example,delivering a continuous, regulated volume to the screw. The pump mayalso be used to increase the fluid pressure within the cannulatedportion of the insert, thereby aiding fluid flow through the insertfenestrations or insert walls, for example. This embodiment may have thefurther advantage that the positive pressure created by the pump withinthe cannulated portion of the insert or bone screw hampers the influx ofunwanted materials or compounds into the device. The pump may beconnected to the cannulated portion of the bone screw or insert asdepicted in FIG. 9, and the pump may also be implanted subcutaneously ifdesired. Examples of pumps which may be suitably used in the practice ofthe current invention are the implantable pumps disclosed in U.S. Pat.No. 4,588,394, for example. Other examples may be relatively simplepumps such as external pumps similar to those used with patientcontrolled anesthesia machines or simple IV pumps. These and other pumptypes and designs which may be currently known or hereinafter discernedby one skilled in the art are to be included within the scope of thisinvention.

In one embodiment of the invention the bone screw may be a fixation nailthat holds two or more bones or bone parts in a fixed spatialrelationship. In this embodiment the exterior of the bone screw shaft isunthreaded. In accordance with the invention, the fixation nail may beadapted for use in the fixation of a variety of bones, including, butnot limited to, femur fixations, humerus fixations and tibia fixations.

Referring now to FIG. 10, there is disclosed a femur fixation nail 1000disposed within a femur 1002. The fixation nail has two ends 1004 and1006 connected by a shaft 1008. The fixation nail includes a cannulatedportion 1010, which is best seen in the cross-sectional view of FIG. 11,and fixation nail fenestrations 1012 along the length of the cannulatedportion 1010. One end of the cannulated portion 1010 of the fixationnail 1000 may be configured to accept a nail insert 1020. This isdemonstrated in FIG. 12 which shows a perspective view of the fixationnail 1000 having internal threads 1014 on one end 1004 of the cannulatedportion 1010 to promote fixation of a nail insert 1020 having threads1025 on one end. As shown in the figures, the fixation nail may defineone or more bores 1030 through its length through which fixation screws1040 and 1050 may be passed in order to affix the fixation nail to thebone. The fixation screws may pass through the fixation nailsubstantially perpendicular to the long axis of the nail or they maypass through the nail at acute or obtuse angles with respect to the longaxis of the nail. The dimensions of a fixation screw that passes throughthe cannulated portion of a fixation nail are desirably selected suchthat the screw does not substantially impede the passage of a substanceto be delivered to the bone. In some instances, the fixation screw mayitself include a bore through its length that allows for the passage ofthe substance.

Referring now to FIG. 13, there is disclosed a humerus fixation nail1300 disposed within a humerus 1302. The fixation nail has two ends 1304and 1306 connected by a shaft 1308. The fixation nail includes acannulated portion 1310, which is best seen in the cross-sectional viewof FIG. 14, and fixation nail fenestrations 1312 along the length of thecannulated portion 1310. One end of the cannulated portion 1310 of thefixation nail 1300 may be configured to accept a nail insert 1320. Thisis demonstrated in FIG. 15 which shows a perspective view of a nailinsert 1320 being inserted into the cannulated portion 1310 of thefixation nail 1300. The fixation nail 1300 has internal threads (notshown) on one end of its cannulated portion 1310 to promote fixation ofthe nail insert 1320 which also has threads 1325 on one end.

Referring now to FIG. 16, there is disclosed a tibia fixation nail 1600disposed within a tibia 1602. The fixation nail has two ends 1604 and1606 connected by a shaft 1608. The fixation nail includes a cannulatedportion 1610, which is best seen in the cross-sectional view of FIG. 17,and fixation nail fenestrations 1612 along the length of the cannulatedportion 1610. One end of the cannulated portion 1610 of the fixationnail 1600 may be configured to accept a nail insert. This isdemonstrated in FIG. 18 which shows a perspective view of the a nailinsert 1620 being inserted into the cannulated portion 1610 of thefixation nail 1600. The fixation nail 1600 has internal threads (notshown) on one end of its cannulated portion 1610 to promote fixation ofthe nail insert 1620 which also has threads 1625 on one end. As shown inthe figures, the fixation nail need not be straight along its entirelength, but may include one or more angles to facilitate the placementof the nail into a bone. The fixation nail may define one or more bores1630 through its length through which fixation screws 1640, 1642, 1644and 1646 may be passed in order to affix the fixation nail to the bone.The fixation screws may pass through the fixation nail substantiallyperpendicular to the long axis of the nail or they may pass through thenail at acute or obtuse angles with respect to the long axis of thenail. The bores may be aligned substantially parallel with respect toone another, substantially perpendicular with respect to one another ormay be aligned at angles between parallel and perpendicular.

As discussed above, in certain applications it may be desirable that thesubstance to be delivered to the bone be stored in a reservoir prior todelivery. FIG. 19 discloses one illustrative embodiment of the inventionin which an IV 1900 serves as a reservoir for delivering a substance toa tibia via the fixation nail of FIG. 18. FIG. 20 discloses analternative embodiment where a pump 2000 serves as the reservoir fordelivering a substance to a tibia via the fixation nail of FIG. 18.

In one embodiment of the invention, the delivery pathway between one ormore insert fenestrations and one or more bone screw fenestrations isdefined by two balloons, each of which is inflated between the outsideof the insert and the inside of the bone screw to form a seal betweenthe insert and the bone screw. This embodiment is exemplified in FIGS.21 and 22. FIG. 21 shows a bone screw insert 2100 having a fenestration2110 along its length. A first balloon 2120 is disposed around theoutside of the insert 2100 above the fenestration 2110 and a secondballoon 2130 is disposed around the outside of the insert 2100 below thefenestration 2110. The insert optionally has threads 2140 at one endthat interlock with bone screw threads 2150 in a bone screw 2160 to helpfix the insert 2100 into the bone screw 2160. The first and secondballoons may be inserted into a bone screw in a deflated state. As shownin FIG. 22, when the insert is in place inside the bone screw theballoons 2120 and 2130 are disposed above and below one or morefenestrations 2170 in the bone screw. Once the insert is in place, theballoons may be inflated to form a seal between the outside 2180 of theinsert 2100 and the inside 2190 of the bone screw 2160, isolating theinsert fenestration 2110 and the bone screw fenestrations 2170 betweenthe balloons. In this manner, the balloons help to define a deliverypathway between one or more insert fenestrations and one or more bonescrew fenestrations.

FIG. 23 shows two different bone-screw inserts 2300 and 2310, eachhaving a pair of balloons 2320, 2330 and 2340, 2350 disposed along itslength and situated above and below an insert fenestration 2360 and2370. The bone-screw inserts have different lengths, such that they maybe adapted for insertion into bone screws of different lengths or may beused to isolate fenestrations at different locations along the shaft ofa given bone screw. Although the insert and bone screw fenestrations ofFIGS. 21-23 are isolated between two inflated balloons, it should beunderstood that other configurations are possible. For example, one ormore insert fenestrations and one or more bone screw fenestrations couldbe isolated between a single inflated balloon and the top end or thebottom end of the bone screw.

An alternative design for a substance delivery device is shown in FIGS.24a and b . In this device a bone screw 2400 is provided with anattachment mechanism, shown as an exterior groove 2410, running alongits length. The bone screw includes a head 2420 that defines alongitudinal bore 2430 having internal threads 2440. A cannulated insert2450 adapted to fit through the longitudinal bore 2430 and into thegroove 2410 is also provided. The insert includes a head 2460 adapted toaccept a tube (not shown), or similar means for delivering a substance,and a plurality of fenestrations 2470 along its length. As shown in FIG.24b , once in place, the insert provides substance delivery pathwaysalong the bone screw from the cannulation at the head 2460 of the insert2450 through the fenestrations 2470. In this illustrative embodiment,the insert 2450 does not extend beyond the threads 2480 of the bonescrew 2400. Although not shown in FIG. 24, the insert may optionallyinclude threads at one end, for example at the bottom of the insert head2460, to engage the internal threads 2440 in the bone screw head 2420 topromote fixation of the insert. FIG. 25 shows a perspective view of thedelivery device of FIG. 24 connected to a substance delivery tube 2500and inserted into the hip bone 2510 of a patient.

FIG. 26 depicts a substance delivery device, similar to that of FIG. 25,where an exterior insert is combined with a fixation nail. FIG. 26ashows a cannulated insert 2600 having a head 2610 adapted to receive atube (not shown), or similar substance delivery means, at one end and aplurality of fenestrations 2620 along its length. As shown in FIG. 26b ,the insert is adapted to fit into a groove 2630 running along theexternal surface of a fixation nail 2640. The fixation nail need not bestraight along its entire length, but may include one or more angles tofacilitate the placement of the nail into a bone. The fixation nail maydefine one or more bores 2650 through its length through which bonescrews (not shown) may be inserted to fix the nail to the bone. Inaddition, the fixation nail may itself include one or more fenestrations2660 along its length. FIG. 27 shows a perspective view of the deliverydevice of FIG. 26b inserted into the tibia 2700 of a patient.

Another aspect of the present invention is a method of administering asubstance to a bone. In one embodiment, the method comprises introducinga cannulated, fenestrated bone screw into a bone, introducing acannulated insert into the bone screw, and introducing a substance to bedelivered into the cannulated portion of the insert. In anotherembodiment, the method comprises attaching a cannulated insert along atleast a portion of an exterior surface of a bone screw, introducing thebone screw into a bone, and introducing a substance to be delivered intothe cannulated portion of the insert. Under some circumstances, one mayfind it advantageous to introduce the insert into or along the bonescrew, in its entirety or only partially, prior to introducing the bonescrew into the bone. This sequence might be preferred in order toshorten the overall surgery time, or to reduce the amount of materialthat enters the bone-screw fenestrations from outside the screw duringscrew insertion, for example. Alternately, other circumstances may makeit more advantageous to introduce the insert into the bone screw, in itsentirety or only partially, after the bone screw is introduced into thebone. This latter sequence might be preferred in order to be able todetermine which screw fenestrations or exterior insert attachmentmechanisms (e.g. grooves) are located at the optimum location fordelivery of the desired substance, and thus what insert configuration orlength should be used to facilitate substance delivery to desiredlocations in or near a bone. Other sequences can be envisioned by oneskilled in the art, such as for example, partially introducing the bonescrew into a bone, partially or completely inserting the insert into oralong the bone screw, and then completing the insertion of the bonescrew into the bone. Even more sequence variations are possible when oneconsiders the additional step of introducing the substance into thecannulated portion of the bone screw insert, and all such sequencevariations are to be included within the scope of this disclosure.

In practicing the current invention it may also be found advantageous todrill a pilot hole in the one or more bones or bone pieces in order tofacilitate introduction of the bone screw. In this regard it may befound advantageous to use bone screws with self-tapping threads, or topre-cut the threads in the bone prior to bone screw insertion.

When the bone screw is a fixation screw, the present invention mayfurther comprise the method of holding or fixing two or more bones orbone pieces in a fixed spatial relationship with respect to each other.Such a method may be desirable when it is desired to deliver a substancesuch as a medicant or therapeutic to the vicinity of a site where aperipheral skeletal fracture or an osteotomy is mended, a spondyloysisor an odontoid fracture repaired, or lumbar facet joints are fused.

The present invention may further comprise the method of delivering asubstance to the vicinity of a bone including the steps of attaching areservoir, a pump, or both, to the bone screws or bone-screw insertsdisclosed herein. Such reservoirs and pumps may aid in the continuous,regulated, or long-term delivery of the desired substance to thevicinity of a bone, thereby facilitating the healing process or theoverall health of the bone and its surrounding tissues.

The bone screw and insert embodiments disclosed herein may be configuredto allow for re-sealing and multiple time or multiple use access to thecannulated portion of the bone screw or insert. In the exemplaryembodiment of FIG. 28, a bone screw 2800 is shown inserted or disposedwithin a bone 2810. An insert 2820 is shown inserted within bone screw2800. A seal, shown as an insert cap 2830, is coupled to the outer orproximal end of insert 2820. In the embodiment shown, insert cap 2830 isan end cap directly coupled to the inner surface of insert 2820. Insertcap 2830 acts to seal the outer or proximal end of insert 2820. In otherembodiments, the seal may be positioned along the shaft of the insert.In some embodiments, cap 2830 is removably coupled to insert 2820, andin other embodiments, cap 2830 may be coupled to insert 2820 via anon-removable (i.e., permanent) coupling. A fluid delivery device, shownas syringe 2840, includes a needle 2850.

Referring to FIG. 29(a) and FIG. 29(b), a schematic cross-sectional viewof insert 2820 is shown according to an exemplary embodiment. Insert2820 includes a shaft 2822, an opening 2824 located at the proximal endof insert 2820, and at least one insert fenestration 2826 locatedthrough shaft 2822. The shaft 2822 of insert 2820 also includes acannulation 2828 formed along at least a portion of shaft 2822. In theembodiment shown, opening 2824 is located at one end of cannulation2828. As shown in FIG. 29(a) and FIG. 29(b), the opening 2824 of insert2820 is closed or sealed by cap 2830. In this arrangement, cap 2830includes an inner surface facing or in communication with cannulation2828. Cap 2830 may be coupled to or attached to insert 2820 by anysuitable means. For example, cap 2830 may be threaded to mate withthreads located within opening 2824, and, in other embodiments, cap 2830may be press fit into opening 2824 or may be attached to opening 2824with an adhesive. In another embodiment, opening 2824 may be locatedalong the sidewall of the insert, and cap 2830 may seal the openingalong the sidewall of the insert.

As discussed above, a substance may be placed in the cannulated portionof an insert, such as insert 2820, so that the substance may bedelivered through the insert fenestrations and through the bone screwfenestrations to the bone. In an exemplary embodiment, insert cap 2830is able to provide multiple-time or reusable access to cannulation 2828of the insert following implantation of the bone screw/insertcombination into the bone. In the exemplary embodiment of FIG. 29(a) andFIG. 29(b), reusable, post-implantation access to cannulation 2828 ofinsert 2820 is provided by self-sealing cap 2830. In this embodiment,cap 2830 comprises a resilient, self-sealing material, and needle 2850pierces through cap 2830 providing access to cannulation 2828. As shownin FIG. 29(a), needle 2850 creates a perforation 2834 that extendsthrough cap 2830. With needle 2850 located within cannulation 2828, asubstance 2832 may be delivered from the fluid delivery device intocannulation 2828. With substance 2832 within cannulation 2828, thesubstance may be delivered through insert fenestrations 2826 and throughbone screw fenestrations as discussed in the various embodiments above.

As shown in FIG. 29(b), once substance 2832 is delivered to insert 2820,needle 2850 may be removed or withdrawn from cap 2830. Once needle 2850is withdrawn, perforation 2834 self-seals to prevent substance 2832 fromflowing out of the proximal end of insert 2820 through perforation 2834.The process of inserting needle 2850 through cap 2830 may be repeated asnecessary to deliver multiple doses of a substance to insert 2820. Whilethe fluid delivery device is shown in FIG. 28 as syringe 2840, invarious other embodiments, needle 2850 may be connected to a variety offluid delivery devices. For example, the fluid delivery device may be apump (e.g., an infusion pump) or a bag or reservoir or fluid bag(similar to an IV bag) coupled to needle 2850 via tubing. In oneembodiment, the fluid delivery device may be a micro-infusion device influid communication with the cannulated portion of the insert and/orbone screw. In this embodiment, the micro-infusion pump may be worn by auser, and a substance may be continuously delivered through the bonescrew and/or insert to promote bone growth.

In various embodiments, cap 2830 may be made from any material orcombination of materials that provides for resealing or self-sealing. Invarious embodiments, cap 2830 may be made from a compliant, non-rigid orresilient material that resiliently expands following withdrawal ofneedle 2850 to seal perforation 2834 caused by needle 2850. In oneembodiment, cap 2830 may be made from a surgical, self-sealing rubber orpolymer, such as surgical silicone rubber.

The post-implantation access to cannulation 2828 of insert 2820 providedby cap 2830 may allow the user to deliver a new or second substance oradditional doses of a same substance to the bone as needed to treat aparticular patient. For example, following implantation of the bonescrew/insert combination, separate doses of antibiotics may be deliveredto a fracture site via insert 2820. In another embodiment, insert 2820may be used for repeated delivery of cancer treating drugs (e.g.,anti-cancer drugs) to the bone in which the bone screw is implanted. Inanother embodiment, bone morphogenic proteins may be delivered inseparate doses to the bone via insert 2820. In other embodiments, anyother substance that may be intermittently delivered to a patient may bedelivered using insert 2820. Further, in contrast to single-use deliverydevices, repeatable access and multiple time delivery via insert 2820may be useful in adjusting or changing the substances delivered viainsert 2820. For example, insert 2820 and resealing cap 2830 allow theuser to change either the dose or the type of substance delivered to apatient each time needle 2850 is inserted through cap 2830. In addition,post-implantation access to cannulation 2828 of insert 2820 by needle2850 may allow for the post-implantation connection of any desired fluiddelivery device (e.g., an IV or infusion pump) to the insert byconnecting the fluid delivery device to needle 2850. This may allow theuser to switch or change the type of fluid delivery device used todeliver fluid to the bone via the bone screw/insert combination. Inother embodiments, needle 2850 may also be connected to a materialremoval device allowing for repeat and resealing access through cap 2830for removal of material from cannulation 2828 of insert 2820, asdescribed below in relation to FIGS. 30(a) and 30(b).

To deliver a dose of substance to a patient by piercing cap 2830 withneedle 2850, the user will need to align needle 2850 with cap 2830following implantation of the implanted bone screw/insert combination.In some embodiments, the bone screw/insert combination may be located asmall distance below the skin such that cap 2830 may be palpated throughthe skin allowing the user to align the needle with cap 2830 by touch.In other embodiments, the bone screw/insert combination may be locatedin a bone deeper below the skin such that alignment via palpation may bedifficult or impossible. In such an embodiment, needle 2850 may bealigned with cap 2830 by imaging the location of the cap 2830 via asuitable imaging device (e.g., via X-ray, CT, etc.).

While the embodiment shown in FIGS. 28, 29(a) and 29(b) shows theresealing cap coupled to an insert, it should be understood that inother embodiments cap 2830 may be coupled directly to a cannulatedbone-screw to seal the proximal opening of a bone-screw. For example, asshown in FIG. 29(c), bone screw 2800 may include a resealing cap, shownas bone screw cap 2860 (similar to cap 2830), that is coupled to orattached to bone screw 2800 such that bone screw cap 2860 seals theproximal opening 2862 of bone screw 2800. Similar to the other bonescrew embodiments discussed herein, bone screw 2800 includes a bonescrew cannulation 2864 and bone screw fenestrations 2866. With needle2850 extending through cap 2860, material may be delivered to a bonethrough bone screw fenestrations 2866, and, as discussed below, materialmay be removed from the bone through bone screw fenestrations 2866. Asshown in FIG. 29(c), bone screw cap 2860 may seal bone screw 2800without an insert disposed within a bone screw cannulation 2864. Inanother embodiment, bone screw cap 2860 may seal the proximal opening2862 of bone screw 2800 with an insert disposed within bone screwcannulation 2864. Further, it should be understood that variousembodiments of resealing caps 2830, 2860 may be used with any of thebone screw and insert embodiments discussed herein.

In other embodiments, the bone screw and insert embodiments disclosedherein may be used as part of a material or tissue removal system. Inthe exemplary embodiment of FIG. 30(a) and FIG. 30(b), a materialremoval system 2900 is shown according to an exemplary embodiment.Material removal system 2900 includes a bone screw 2910, a bone screwinsert 2930 and a material removal device, shown as suction device 2950(e.g., a pump, vacuum, etc.). Bone screw 2910 includes a sidewall 2912,a threaded portion, shown as threads 2914, formed on the inner surfaceof sidewall 2912, and a bone screw cannulated portion 2916. Bone screw2910 also includes at least first fenestrations 2918 and secondfenestrations 2920. In the orientation of FIG. 30(a), fenestrations 2918are located above (i.e., closer to the proximal end of bone screw 2910)fenestrations 2920.

Insert 2930 includes a first expandable portion, shown as first balloon2932, and a second expandable portion, shown as second balloon 2934.Insert 2930 includes an insert fenestration 2936 located betweenballoons 2932 and 2934. As discussed above regarding FIGS. 21-23,balloons 2932 and 2934 may be inflated to form seals with the innersurface of bone screw 2910 to provide for isolation of one or more ofthe bone screw fenestrations. Insert 2930 includes a threaded portion,shown as threads 2938, that engages with threads 2914 of bone screw2910. While material removal system 2900 is shown and described with aninsert that includes expandable sections, it should be understood thatmaterial removal system 2900 may utilize any of the bone screw/insertcombinations discussed herein.

Material removal system 2900 includes a material removal device, shownas suction device 2950, connected to insert 2930 via a tubing 2952.Suction device 2950 is configured to extract or aspirate material fromcannulated portion 2916 of the bone screw and from the area surroundingthe bone screw. In various embodiments, suction device 2950 may be amotorized suction device or may be a manual suction device (e.g., asyringe). In the embodiment shown in FIG. 30(a), balloons 2932 and 2934are inflated to isolate fenestrations 2918. As illustrated by arrows2954, suction device 2950 applies a vacuum to insert 2930 via tubing2952 such that material is drawn in through fenestrations 2918 and ismoved through the insert and tubing to reach the suction device. Thus,in this manner, suction device 2950 allows for removal or harvesting ofmaterial adjacent fenestrations 2918.

Various types of material may be removed from a patient using materialremoval system 2900. In addition, material may be removed for variouspurposes, including for diagnostic testing and/or for subsequentimplantation. For example, in one embodiment, bone marrow may beharvested using material removal system 2900 to be used for bone marrowdonation or for diagnostic testing. Other materials, such as blood, maybe removed for diagnostic testing. In some embodiments, variousmaterials may be removed from the bone screw using suction device 2950to test for the presence of infection within the bone at the site ofimplantation of the bone screw.

In one embodiment, material removal system 2900 may be used to harvestosteoprogenitor cells from the bone of the patient into which bone screw2910 is inserted. In one such embodiment, the harvested osteoprogenitorcells harvested using material removal system 2900 may then be implantedinto another area of the patient (e.g., another bone) where bone growthis desired. In one specific embodiment, material removal system 2900 maybe used to remove osteoprogenitor cells from one location in a patient,and then the removed osteoprogenitor cells may be implanted using one ofthe bone screw/insert combinations discussed herein located at anotherposition within the patient. In various embodiments, the osteoprogenitorcells may be combined with other materials (e.g., calcium phosphate,hydroxylapatite, demineralized bone matrix, etc.) that may facilitate orenhance bone growth that results from the osteoprogenitor cells.

As shown in FIG. 30(a) and FIG. 30(b), bone screw 2910 includes aplurality of fenestrations (e.g., fenestrations 2918 and 2920). As usedas part of material removal system 2900, insert 2930 and the pluralityof fenestrations of bone screw 2910 allow the user to select or toisolate individual fenestrations or groups of fenestrations toselectably harvest material through the selected fenestrations. Forexample, in FIG. 30(a), insert 2930 is shown harvesting material throughfenestrations 2918. In FIG. 30(b), insert 2930 is shown positionedwithin bone screw 2910 such that fenestrations 2920 are isolated betweenballoons 2932 and 2934. In this position, operation of suction device2950 allows for removal of material through fenestrations 2920, asdepicted by arrows 2956. This arrangement allows the user to selectivelytake samples of removed material from various positions within the bone.

In one embodiment, insert 2930 may include a resealing cap, such as cap2830, that allows suction device 2950 to be connected to the cannulatedportion of the insert via a needle, such as needle 2850. In otherembodiments, the material removal device may be a device other than asuction-based aspiration device. For example, the material removaldevice may be any other suitable material removal device such as anabsorbent device (e.g., a swab) that absorbs material located withineither the cannulated portion of the bone screw or the insert.

In other embodiments, a bone screw may include one or more fenestrationsshaped as a slot extending longitudinally along the shaft of a bonescrew. Referring to FIG. 31, bone screw 3000 is shown according to anexemplary embodiment. Bone screw 3000 includes a shaft 3010 and bonescrew threads 3020. Bone screw 3000 includes a cannulation 3030, a firstfenestration 3040, a second fenestration 3050, and a third fenestration3060. First fenestration 3040 and second fenestration 3050 areconfigured as rectangular slots that extend in the longitudinaldirection along shaft 3010. In the embodiment shown, the length of firstfenestration 3040 in the longitudinal direction is approximately aquarter of the longitudinal length of shaft 3010 and the length ofsecond fenestration 3050 in the longitudinal direction is approximatelyhalf of the longitudinal length of shaft 3010. Third fenestration 3060is shown as a smaller slot-shaped fenestration located near the distalend of bone screw 3000.

In other embodiments, fenestrations, such as fenestrations 3040, 3050and 3060, may be of other lengths relative to shaft 3010 (e.g., ⅛ of thelength of shaft 3010, ¼ of the length of shaft 3010, ½ of the length ofshaft 3010, and ¾ of the length of shaft 3010, etc.). In the embodimentshown in FIG. 31, threads 3020 are shown including gaps or spaces at thelocation of fenestrations 3040, 3050 and 3060. In other embodiments,threads 3020 may be contiguous threads that extend above or overlapfenestrations 3040, 3050 and 3060.

Referring to FIG. 32, a femur fixation nail 3100 disposed within a femur1002 is shown. Fixation nail 3100 includes a shaft 3110 which iscannulated. Fixation nail 3100 is similar to fixation nail 1000 shown inFIG. 10 except that fixation nail 3100 includes three rectangular-shapedslot fenestrations 3120, 3130 and 3140 that extend in the longitudinaldirection along shaft 3110. In the embodiment shown, all of thefenestrations 3120, 3130 and 3140 are generally of the same size andshape.

It should be understood that while FIGS. 31 and 32 show two bone screwembodiments including slot-shaped fenestrations, any of the bone screwembodiments discussed herein may include one or more slot-shapedfenestrations. Further, while the bone screw embodiments of FIGS. 31 and32 show bone screws having three slot-shaped fenestrations, it should beunderstood that the bone screw embodiments may include any number ofslot-shaped fenestrations (e.g., 1, 2, 4, 5, 6, 7, 8, etc.) as neededfor a particular application, procedure, patient, etc. While in theexemplary embodiments the slot-shaped fenestrations are shown asrectangular in shape, other shapes may be used (e.g., oval, elliptical,diamond, triangular, etc.). Further, while FIGS. 31 and 32 depictslot-shaped fenestrations with longitudinal axes extending in thedirection of the longitudinal axis of the shaft of the bone screw,slot-shaped fenestrations may assume other positions or orientationsrelative to the shaft of the bone screw. In one exemplary embodiment, aslot-shaped fenestration may be a circumferentially orientedfenestration such that the longer axis of the fenestration isperpendicular to the longitudinal axis of the shaft (as shown in FIG.10).

Referring to FIG. 33(a), FIG. 33(b) and FIG. 33(c), a bone screw 3210 isshown implanted or disposed within a bone 3200. Bone screw 3210 includesa sidewall 3212, a threaded portion, shown as threads 3214, formed onthe inner surface of sidewall 3212, and a bone screw cannulated portion3216. As shown, bone screw 3210 includes first fenestrations 3218 andsecond fenestrations 3220. Fenestrations 3218 and 3220 are slot-shapedfenestrations that extend longitudinally along sidewall 3212. Bone screw3210 may be a threaded bone screw, such as bone screw 3000, a fixationnail, such as femur fixation nail 3100, or any other bone screwembodiment disclosed herein. In the orientation of FIG. 33(a),fenestrations 3218 are located above (i.e., closer to the proximal endof bone screw 3210) fenestrations 3220.

An insert 3230 is shown positioned within cannulated portion 3216 ofbone screw 3210. Insert 3230 includes a first expandable portion, shownas first balloon 3232, and a second expandable portion, shown as secondballoon 3234. Insert 3230 includes an insert fenestration 3236 locatedbetween balloons 3232 and 3234. In the embodiment shown in FIGS. 33(a),33(b) and 33(c), the longitudinal length, L1, of fenestrations 3218and/or the longitudinal length, L2, of fenestrations 3220 are greaterthan the longitudinal length, L3, of the portion of insert 3230 that islocated between first balloon 3232 and second balloon 3234.

The relative sizing of fenestrations 3218 and 3220 and the portion ofthe insert between the upper and lower balloons allows for selection orisolation of a portion of slot-shaped fenestrations 3218 and 3220. Asshown in FIG. 33(a), insert 3230 may be positioned such that insertfenestration 3236 is located adjacent the upper ends of fenestrations3218. With insert 3230 in this position, balloons 3232 and 3234 may beinflated to provide for isolation or selection of the upper portions offenestrations 3218. With the upper portions of fenestrations 3218isolated, a substance may be delivered through insert fenestration 3236to the portion of bone 3200 adjacent the isolated section offenestrations 3218, and/or a material may be removed from the portion ofbone 3200 adjacent the isolated section of fenestrations 3218 via insert3230, as discussed in the various embodiments above.

In general, upper balloon 3232 is expanded to form an upper seal betweenthe outer surface of the balloon and the inner surface of the bone screwand/or the tissue adjacent the bone screw fenestration, and lowerballoon 3234 is expanded to form a lower seal between the outer surfaceof the balloon and the inner surface of the bone screw and/or the tissueadjacent the bone screw fenestration. Thus, with the balloons expanded,the lower surface of upper balloon 3232 and the upper surface of lowerballoon 3234 define a sealed chamber or section 3242 that isolates aportion of the adjacent bone screw fenestration. Insert fenestration3236 is located within sealed section 3242, and thus, a pathway isdefined between the portion of bone 3200 adjacent the sealed section3242 and the proximal end of insert 3230. A substance may be deliveredto bone 3200 via the pathway and/or a material may be removed from bone3200 via the pathway as discussed above in the various embodiments.

Each of FIGS. 33(a), 33(b), and 33(c) show the isolation of variousportions of fenestrations 3218 according to various exemplaryembodiments. In the position shown in FIG. 33(a), upper balloon 3232 isexpanded to form an upper seal with the inner surface of bone screw 3210above fenestrations 3218, and lower balloon 3234 is expanded to form alower seal with both the tissue (e.g., bone 3200) adjacent tofenestrations 3218 and with the inner surface of bone screw 3210 that islaterally adjacent to fenestrations 3218 (not visible in the sectionview of FIG. 33(a)). In the position shown in FIG. 33(b), both upperballoon 3232 and lower balloon 3234 are expanded to form seals with thetissue (e.g., bone 3200) adjacent to fenestrations 3218 and with theinner surface of bone screw 3210 that is laterally adjacent tofenestrations 3218 (not visible in the section view of FIG. 33(b)). Inthe position shown in FIG. 33(c), lower balloon 3234 is expanded to forma lower seal with the inner surface of bone screw 3210 belowfenestrations 3218, and upper balloon 3232 is expanded to form an upperseal with both the tissue (e.g., bone 3200) adjacent to fenestrations3218 and with the inner surface of bone screw 3210 that is laterallyadjacent to fenestrations 3218 (not visible in the section view of FIG.33(c)). Also as shown in FIG. 33(c), an upper portion of balloon 3234 isshown expanding to seal against the lower surface 3238 of fenestrations3218 by expanding through laterally through fenestration 3218. It shouldbe understood that, both balloons 3232 and 3234 may be configured toallow for expansion through the fenestrations to provide for sealing asshown in FIG. 33(c).

While FIGS. 33(a), 33(b), and 33(c) show three exemplary positions atwhich insert 3230 may be used to isolate portions of fenestrations 3218,it should be understood that insert 3230 may be moved to any positionrelative to the fenestration as desired by the user. In the embodimentshown, the positioning may be selected by advancing insert 3230 throughthreads 3214 of bone screw 3210 via cooperation of insert threads 3240.While FIGS. 33(a), 33(b) and 33(c) depict selection of various portionsof fenestrations 3218, it should be understood that insert 3230 may besized and configured such that portions of any fenestration of bonescrew 3210 may be selected as discussed above.

Referring to FIG. 34, another aspect of the invention is disclosed. Thebone screw 3400 coupled with an insert 3402 can include any feature inany embodiment discussed above. In some embodiments, the bone screw 3400is used for delivering multiple substances into a bone 3408 in a delayedfashion. In some embodiments, a first substance 3404 may be delivered toa desired location in the bone 3408. The first substance 3404 changesover time into an at least partially solid hardened material. Forexample, the first substance 3404 is bone void filler, such as bonecements. After the first substance 3404 changed into a semi-solid orfully solid state, a second substance 3406 may be delivered into thebone 3408. In some embodiments, the substance may be delivered throughan insert 3402 positioned in the bone screw 3400. In one embodiment, thefirst and second substances are delivered through the same insert 3402.In another embodiment, the first and second substances are deliveredthrough different inserts. In some embodiments, the solid hardenedmaterial of the first substance 3404 is permeable material and allowsthe second substance 3406 to transport through. In some embodiments, thesecond substance 3406 may transport through the solid hardened materialby diffusion. In some other embodiments, the second substance 3406 mayreach to a desired location in the bone through pores or cracks of thesolid hardened material of the first substance 3404. In someembodiments, the second substance 3406 can be in a liquid state, in agaseous state or in a mixed state. In some other embodiments, the secondsubstance 3406 may be delivered into the bone while the first substance3404 is changing into a solid state. Additional substances, such as athird substance or medicant may be delivered the bone in the samefashion, through the first and/or second substance.

Further modifications and alternative embodiments of various aspects ofthe invention will be apparent to those skilled in the art in view ofthis description. Accordingly, this description is to be construed asillustrative only. The construction and arrangements of the bone screwsand inserts, as shown in the various exemplary embodiments, areillustrative only. Although only a few embodiments have been describedin detail in this disclosure, many modifications are possible (e.g.,variations in sizes, dimensions, structures, shapes and proportions ofthe various elements, values of parameters, mounting arrangements, useof materials, colors, orientations, etc.) without materially departingfrom the novel teachings and advantages of the subject matter describedherein. Some elements shown as integrally formed may be constructed ofmultiple parts or elements, the position of elements may be reversed orotherwise varied, and the nature or number of discrete elements orpositions may be altered or varied. The order or sequence of anyprocess, or method steps may be varied or re-sequenced according toalternative embodiments. Other substitutions, modifications, changes andomissions may also be made in the design, operating conditions andarrangement of the various exemplary embodiments without departing fromthe scope of the present invention.

What is claimed is:
 1. A method for delivering multiple substances in adelayed fashion to a bone of a patient, comprising: providing acannulated bone screw, wherein the bone screw comprises first and secondfenestrations disposed along a shaft of the bone screw and connecting toa cannulation of the bone screw; inserting an insert into the bonescrew; creating an aperture in skin of a patient; inserting the bonescrew into the bone of the patient through the aperture; delivering afirst substance into the bone through the bone screw, wherein the firstsubstance changes over time into an at least partially solid hardenedmaterial; and delivering a second substance into the bone through thebone screw and through the first substance after the first substance haschanged into the at least partially solid hardened material; wherein thefirst and second substances are delivered into the bone through theinsert; and wherein the insert is moveable within the cannulation of thebone screw to deliver the first substance through at least one of thefirst and second fenestrations and to deliver the second substancethrough at least one of the first and second fenestrations.
 2. Themethod of claim 1, wherein the solid hardened material of the firstsubstance is a permeable material that allows the second substance totransport through.
 3. The method of claim 1, wherein the secondsubstance transports through the first substance by diffusion.
 4. Themethod of claim 1, wherein the second substance reaches to a desiredlocation in the bone through pores or cracks in the hardened solidmaterials of the first substance.
 5. The method of claim 1, furthercomprising delivering a third substance into the bone while the firstsubstance is changing into a solid hardened material.
 6. The method ofclaim 1, further comprising: removing the insert without removing thebone screw before delivering the second substance; treating the insertwith a treatment intended to reduce infection in the bone and clean acannulation of the insert; and recoupling the treated insert to the bonescrew.
 7. The method of claim 1, further comprising providing a secondinsert and coupling the second insert to the bone screw.
 8. The methodof claim 1, wherein the insert is moveable within the cannulation of thebone screw between a first position to deliver the first substancethrough the first fenestration and a second position to deliver thesecond substance through the second fenestration.
 9. The method of claim1, wherein the first substance includes bone cements and the secondsubstance includes at least one of bone morphogenic proteins,osteoprogenitor cells, calcium phosphate, antibiotics, and anti-cancerdrugs.
 10. A method for delivering multiple substances in a delayedfashion to a bone of a patient, comprising: providing a cannulated bonescrew, wherein the bone screw comprises first and second fenestrationsdisposed along a shaft of the bone screw and connecting to a cannulationof the bone screw; inserting an insert into the bone screw; creating anaperture in skin of a patient; inserting the bone screw into the bone ofthe patient through the aperture; delivering a first substance into thebone through the bone screw, wherein the first substance changes overtime into an at least partially solid hardened material; delivering asecond substance into the bone through the bone screw and through thefirst substance after the first substance has changed into the at leastpartially solid hardened material; wherein the first and secondsubstances are delivered into the bone through the insert; removing theinsert without removing the bone screw before delivering the secondsubstance; treating the insert with a treatment intended to reduceinfection in the bone and clean a cannulation of the insert; andrecoupling the treated insert to the bone screw.